Tube transmitter circuit arrangement



July 11, 1933. w BUSCHBECK 1,917,697

TUBE TRANSMITTER CIRCUIT ARRANGEMENT Filed May 28, 1929 INVE NTOR WERNER BUSCHBECK ATTORNEY Patented July 11, 1933 UNITED STATES PATENT OFFICE WERNER BUSCHBECK, OF BERLIN, GERMANY, ASSIGNOR T0 TELEFUNKEN GESELL- SCHAFT FUR DRAHTLOSE TELEGRAPHIE lvI. B. H., 0F BERLIN, GERMANY, A CORPO- RATION OF GERMANY TUBE TRANSMITTER CIRCUIT ARRANGEMENT Application filed May 28, 1929, Serial No.

This invention reates to thermionic devices and in particular to devices used in short wave communication.

An object of this invention is to provide a thermionic generator which will not radiate waves at frequencies other than the desired frequency.

Another object of this invention is to provide a novel thermionic signaling device in which means is provided to obviate the necessity of maintaining symmetrical capacity to ground effect between the circuits or portions thereof.

Other objects and advantages will become apparent from the following specification, and therefrom when read in connection with the drawingherein referred to and in which Figure 1 shows one circuit arrangement of a thermionic device arranged in accordance with the present invention; while Figure 2 shows a modification of the arrangement shown in Figure 1.

It has been found in practice that in circuit schemes of the kind illustrated in Figure 1, disturbing or stray waves are liable to be caused by the plate direct current supply lead A. This is due to the fact that the potentials prevailing across the terminals of condenser C connected between the filament 1 and oscillation circuit 2', 3, 4 connected to the anode 5 of tube 0, are mostly higher than what would have to be expected according to theory. Inasmuch as both the plate end as well as the lower part of the oscillation circuit exhibit distributed capacitances to ground which are exactly alike only in rare cases, a compensating current liable to exceed the plate alternating current many times in value will flow by way of the blocking condenser C instead of merely the pure ac- 366,582, and in Germany June 30, 1928.

tive current of the tube. The result is-that this large current sets up disturbing potentials across the condenser C and these po tentials can be obviated, for instance, by renewed choking of lead A.

Another simple means according to the invention consists in connecting the currentsupply choke-coil D not directly with'Cg, but with a distinct condenser 0 which as a matter of fact, passes only the small radio frequency current leaking off by way of D so that the direct current lead A is really united with a point which has no radio fre quency potential. to ground. This circuit arrangement is illustrated in Figure 2. Choking and damping of lead A will then no longer be necessary. The identical scheme may be adopted when the oscillation circuit .with the condenser lead (potential divider) is connected in the grid circuit of the tube.

I claim:

Signaling means comprising, a thermionic tube device having acathode and cold electrodes, an oscillation circuit comprising a capacity and an inductance connected in parallel, means connecting adjacent ends of said capacity and said inductance to a cold electrode, means for applying direct current potential to said cold electrode including a choke coil connected at one end to a point intermediate the terminals of said inductance, capacitive means for connecting a point intermediate the terminals of said parallelcapacity to said cathode, and capacitive means for connecting the free end of said choke coil to said cathode, said last named capacitive means and connection being entirely separate from said first named capacitive connecting means.

WERNER BUSCHBECK. 

